Interplanetary shock wave angles are key to infrastructure threat

Giant shock waves emanating from the Sun can give us some breathtaking auroras here on Earth. They can also cause energy surges that can damage our infrastructure, says a new study that looks at how their angles of impact shape their consequences.

According to NASA, interplanetary shocks happen when a fast stream of charged particles known as the solar wind travels from the Sun and it overtakes a slower stream, “just like a boat moving through a river creates a wave.” The space agency’s Magnetospheric Multiscale mission, or MMS, first measured interplanetary shocks in 2019 thanks to its suite of highly precise analytical tools mounted on four individual spacecraft in orbit.

When these waves slam into the Earth’s magnetosphere, they compress it, which can lead to the strikingly colorful displays of the aurora borealis. But they can also cause geomagnetically generated ground currents on our planet’s surface which, a team of NASA and university-based researchers say, can damage infrastructure that conducts electricity such as oil and gas pipelines, railways, powerlines, and submarine cables.

What’s more, the orientation at which these waves hit Earth can dramatically affect their disruptive power, the researchers found. In particular, when the waves hit head-on rather than at an angle, they generate a greater ground-based current.

The team reached this conclusion after matching data on interplanetary shocks and the solar wind with readings of geomagnetically induced currents from a natural gas pipeline in Mäntsälä, Finland. This part of the world generally experiences aurorae during times of heightened solar activity. The researchers also found that the geomagnetic storms caused by interplanetary shocks tended to happen around magnetic midnight, a time when the Earth’s North Pole was between Mäntsälä and the Sun.

While Mäntsälä sits at a high latitude, the researchers point to the recent magnetic storms that hit Earth in May of this year as an example of how far reaching the effects of such activity can be.

“The auroral region can greatly expand during severe geomagnetic storms,” said study lead Denny Oliveira of NASA’s Goddard Space Flight Center. “Usually, its southernmost boundary is around latitudes of 70 degrees, but during extreme events it can go down to 40 degrees or even further, which certainly occurred during the May 2024 storm – the most severe storm in the past two decades.”

The researchers say that the interplanetary shocks are predictable about two hours before they strike Earth, so understanding their approach angle could allow keepers of infrastructure facilities on Earth to respond appropriately – especially if a wave is heading straight at us, rather than at an angle.

“One thing power infrastructure operators could do to safeguard their equipment is to manage a few specific electric circuits when a shock alert is issued,” said Oliveira. “This would prevent geomagnetically induced currents reducing the lifetime of the equipment.”

The research has been published in the journal Frontiers in Astronomy and Space Sciences.

Source: Frontiers

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